It is proposed to investigate a new approach towards a high energy rechargeable lithium battery system for use in percutaneous or transcutaneous transmission of energy in the artificial heart program e.g. for Ventricular Assist Systems (VAS). The new approach is based on the development of a more energetic cathode material which operates by the topochemical insertion mechanism of lithium ions during the discharge process. In this approach, a specially prepared amorphous trisulfide would be used alone or with an addition of TiS2 as a high energy cathode material. This approach appears very promising for reaching even higher rate capabilities with good rechargeability. It is anticipated that the new approach could provide rechargeable lithium batteries with practical energy densities in the range of 98-143 WH/Kg compared to only 24-33 WH/Kg for the present nickel-cadmium cells. The importance of such a large increase in energy density for this field needs hardly any elaboration. There are many important problems that need to be solved on the road towards practical hardware, but in Phase I, we propose to concentrate on the problem of the cathode, its energy density and cycling capacity. On this basis the complete cell development would then be undertaken in Phase II for the VAS device applications.